SCORPIO wrote:I want to convert all of my existing aquarium lights into wifi controlled on/off system. Need help and expert advice. I have basic knowledge of electronics.

It doesn't make much of a sense converting lights to WI-Fi control just for the sake switching it on or off(IMO our timer perform better).You can make a controller or buy it off the shelf to control almost all the funtions.

If you really want to go the microcontroller way, use it to control temperature, lights and CO2. Its a longer project but worth the effort.

this is why I said for on-off control timers are the best/easiest.Secondly in case you go with DIY you might end up spending more on building a controller than what you spend on off the shelf solutions.